Definition. Cysts are hollow tumors filled with fluid or semi-solid contents. They are classified according to their mode of development:

1. Cysts formed in already existing spaces such as sebaceous cysts in the sebaceous glands of the skin; mucous cysts in mucous glands, and distension cysts in ducts of large glands like the salivary, lacteal, hepatic, etc.

2. Cysts of new formation into the tissue spaces from the effusion of blood or plasma.

3. Congenital cysts known as dermoids.

4. Cysts of parasitic origin.

The only cyst with which the chiropodist ordinarily comes in contact is of the sebaceous variety.

Sebaceous Cyst. A sebaceous cyst is a tumor resulting from retained sebum (secretion of the sebaceous glands).

They sometimes, though rarely, are found on the soles of the feet. They range in size from a millet seed to the size of an egg or larger; they may be globular or flattened. They may be single or multiple; the skin over them is normal in color and smooth, or white if distended, red if inflamed. They grow very slowly and ordinarily persist indefinitely, but calcareous changes are common. Not infrequently they break down and ulcerate. The wall is made up of connective tissue lined with epithelium and the secretion if chemically altered, becomes fluid, semi-fluid, cheesy or purulent.

Treatment. Spontaneous cure often occurs when a cyst becomes inflamed and suppurates. The pus is evacuated either spontaneously or by incision, following which the walls of the sac adhere and its cavity is obliterated.

Treatment directed toward the obliteration of the sac is the only procedure which gives promise of permanent cure; mere puncture and evacuation will effect only temporary relief, the sac soon filling again.

Incision followed by dissection and removal of the sac, either intact or punctured, is radical and efficient.

Puncture and evacuation, followed by swabbing out with pure phenol or strong iodin, may set up an inflammatory reaction within the sac, which acts similarly to the suppurative process, causing adhesion of the walls, thus preventing a recurrence.